Minimum irradiance required to inhibit microbial growth to prevent ventilatorassociated pneumonia by an endotracheal tube equipped with blue LEDs

Artificial respiration is saving lives especially in the COVID-19 pandemic, but it also carries the risk to cause ventilator-associated pneumonia (VAP). VAP is one of the most common and severe nosocomial infections, often leading to death and adding a major economic burden to the healthcare system. To prevent a proliferation of microbial pathogens that cause VAP, an endotracheal tube (ETT) equipped with blue LEDs (LED-ETT) was developed. This blue wavelength exhibits antimicrobial properties but may also harm human tracheal cells at higher irradiances. Therefore, the aim of this study was to find the minimal required irradiance for microbial reduction of 1 log level in 24 h by applying LED-ETTs. A LED-ETT with 48 blue LEDs (450 nm) was fixed in a glass tube, which served as a trachea model. The investigation was carried out with irradiations of 4.2, 6.6 and 13.4 mW/cm² at 37 °C for 24 h. The experiments were performed with Acinetobacter kookii as a surrogate of Acinetobacter baumannii, which is classified as critical by the WHO. Samples of A. kookii suspensions were taken every 4 h during irradiation from the trachea model. Bacteria concentrations were quantified by determining colony forming units (CFU)/ml. A homogeneous irradiance of only 4.2 mW/cm² generated by the blue LEDs, at a LED forward current of 3.125 mA, is sufficient to achieve a 1 log reduction of A. kookii within 24 h. The total irradiation dose within this period was 360 J/cm2. Human cells survive this dose without cellular damage. Previous studies revealed that the pathogen A. baumannii is even more sensitive to blue light than A. kookii. Therefore, blue LED-ETTs are expected to reduce A. baumannii without harming human tracheal cells.

Functional relevance of macular telangiectasia (MacTel) area on multicolour imaging in type 2 MacTel

Purpose: To analyse the correlation between area of macular telangiectasia (MacTel) involvement on multicolour (MC) imaging, disease stages and visual acuity in type 2 MacTel. Methods: In this retrospective analysis of MC images, confirmed cases of type 2 MacTel were graded into different disease stages as per Gass and Blodi and Yannuzzi et al classification systems. The ‘MacTel area’ was calculated by marking the outer boundary of an area with abnormally increased reflectivity to confocal blue wavelength light. At every follow-up visit, best-corrected visual acuity, MacTel area and stage of disease on the MC image was documented. Analyses between disease stage, MacTel area and visual acuity was carried out. Results: In total, 92 eyes of 49 patients were included in the study. The mean age was 59.6 ± 8.96 years. About 182 high-quality gradable MC images were available for analysis. There was a statistically significant difference in the visual acuity ( p < 0.001) and area of involvement ( p < 0.001) in the non-proliferative and proliferative type 2 MacTel groups. An increase in disease severity stage statistically correlated positively with Mactel area ( r = 0.544; p < 0.001) and logMAR visual acuity ( r = 0.329; p < 0.001). Over time, there was a significant increase in area of MacTel involvement ( p = 0.012) with an associated decrease in the visual acuity ( p = 0.023). Conclusion: The MacTel area measured on MC imaging showed a strong positive correlation with disease stage and a negative correlation with visual acuity. This could serve as a useful biomarker in clinical trials and understanding the natural history of the disease.

Novel Blue-Wavelength-Blocking Contact Lens with Er3+/TiO2 NPs: Manufacture and Characterization

Thermally stable titanium dioxide nanoparticles (TiO2 NPs) doped with erbium ions (Er3+) are characterized by uniformity, low excitation energy, and high surface area. The impregnation methodology was used to enhance the optical properties of TiO2 NPs impregnated with various Er3+ ion contents. The synthesized Er3+/TiO2 samples were characterized by energy dispersive X-ray (EDX), metal mapping, UV–Visible spectrum, field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The Er3+ ions, per our findings, were well-distributed on the TiO2 surface of the anatase phase and there was an insignificant difference in particle size, but there was no change in the particle shapes of the Er3+/TiO2 NPs structure. The maximum band gap degradation occurred with 1.8 wt % of Er3+/TiO2, where the energy gap degraded from 3.13 to 2.63 eV for intrinsic TiO2. The synthesized Er3+/TiO2 samples possess predominantly finely dispersed erbium ion species on the surface. Er3+ ions agglomeration on the surface increased with increasing ions in each sample. We found that 0.6 wt/vol % of Er+3/TiO2 is the best optical coating and produced satisfying results in terms of blocking the transmittance of blue wavelength without reducing the image quality.

Negative Bias Instability of InZnO-Based Thin-Film Transistors Under Illumination Stress

In this study, we investigated the threshold voltage (Vth) instability of solution-processed indium zinc oxide (IZO) thin film transistors (TFTs) prior to and after negative bias illumination stress (NBIS) with varying carrier suppressors (Ga, Al, Hf, and Zr). Variations in electrical properties of the IZO-based TFTs as a function of carrier suppressors were attributed to the differences in metal-oxygen bonding energy of the materials, which was numerically verified by calculating the relative oxygen deficient ratio from the X-ray photoelectron spectroscopy analysis. Furthermore, the values of Vth shift (ΔVth) of the devices subjected to negative gate bias stress under 635 nm (red), 530 nm (green), and 480 nm (blue) wavelength light irradiation increased as the incident photon energy increased. IZO TFTs doped with Ga atoms demonstrated weaker metal-oxygen bonding energy compared to the others and exhibited the largest ΔVth. This result was attributed to the suppressor-dependent distribution of neutral oxygen vacancies which determine the degrees of photon energy absorption in the IZO films. Then, the ΔVth instability of IZO-based TFTs under NBIS correlated well with a stretched exponential function.

The importance of melatonin in the regulation of metabolism, eating behavior, sleep, and the prospects for the use of melatonin drugs for obesity treatment

Melatonin is a special hormone that act as an internal synchronizer of circadian rhythms, the organism physiology and behavior to the environmental day and night and seasons of the year. The present urban society and the industrial production processes as organized should be considered, as both depend on the presence of indoor lights during the night and include the profuse use of electronic devices whose screens are rich in blue wavelength light. Light during the night delays the beginning of the secretory episode of melatonin and blunts its peak, causing chronic hypomelatoninemia. Hypomelatonemia, that causes deprivation of sleep and eating behavior disorders, along with low physical activity, can be the reason of the obesity, «non-infectious epidemic of the 21st century». According to this, the use of melatonin drugs for obesity treatment can be effective. Further prospective, controlled, randomized trials in this area are required to confirm this hypothesis.

155 Evening blue light exposure, maternal glucose and infant birth weight

Introduction During pregnancy, the use of light-emitting electronic devices before bedtime may contribute to or exacerbate sleep problems. Exposure to blue-wavelength light in particular from these devices may affect sleep by inhibiting melatonin release and causing neurophysiologic arousal which may affect the uterus environment. However, the health consequences of blue-wavelength light on maternal glucose level and fetus development is poorly understood. The purpose of this study was to test the hypothesis that nocturnal blue-light exposure is associated with maternal glucose level and infant’s birth weight. Methods A group of pregnant women aged 24-39 years old who wore 7-day actigraphy, and completed questionnaires including Pittsburgh Sleep Quality Index participated in the study. Infant’s birth weight (n=41) and fasting glucose level (n=30) was abstracted from mothers’ medical charts. Blue-wavelength light exposure was obtained from actigraphy recordings. Unadjusted linear regression analyses were performed to determine sleep characteristics that were associated with fasting glucose and infant’s weight (p&lt;0.2). Using infant’s birth weight and fasting glucose as outcome variables, confounding variables were evaluated in full linear regression models as independent variables. Results The mean gestational age was 30.66 (Standard Deviation (SD) 3.46) weeks. The mean fasting glucose, infant’s birth weight and gestational age at delivery were 95.73 mg/dL (SD 24.68), 3261 gr (SD 470) and 38.78 (SD 1.69), respectively. In unadjusted analysis, infant birth weight was significantly associated with only blue light value (μW/cm2) (β=76.98, p=0.002) and remained significant (β=78.26, p=0.003) after adjusting for BMI, maternal age and gestational diabetes. Fasting glucose was associated with blue light value (β=2.81, p=0.055) and became significantly associated (β=78.26, p=0.003) after adjusting for sleep duration, parity and gestational diabetes. The coefficient demonstrates that for each unit increase in the evening blue light exposure, there is a 78 gr increase in infant weight after controlling the effect of maternal age, BMI and gestational diabetes. Conclusion Evening blue light exposure during mid and late pregnancy may alter maternal glucose regulation and placental nutrient transport to fetus, but these remain to be studied. This study may shed light on future research on the effect of evening light exposure on pregnancy outcomes. Support (if any) National Institutes of Health (R00-NR013187)

Blue Light Photodynamic Therapy With Curcumin and Riboflavin in the Management of Periodontitis: A Systematic Review

Introduction: The aim of this article was to evaluate reports in the scientific literature that used antimicrobial photodynamic therapy (aPDT) with a blue light source and curcumin and riboflavin as photosensitizers in the management of periodontitis. Methods: The search was conducted in electronic databases, including PubMed, Web of Science, and Scopus, with the keywords "photodynamic therapy", "antimicrobial photodynamic therapy", "laser activated disinfection", "photoactivated disinfection", "light activated disinfection" "LED", "Periodontitis", "Curcumin", "Riboflavin", and "periodontitis" from 2012 to 2020. Results: After evaluating a total of 24 relevant articles, 13 articles were selected, full texts were read, and the data were extracted and placed in a table. Conclusion: Reviewing articles showed that curcumin as a photosensitizer activated by a blue wavelength is effective in the elimination of the various bacterial species involved in periodontal disease, and to the best of our knowledge, there is no study that has shown this substance does not reduce bacteria. According to the result of the articles, riboflavin as a photosensitizer activated by blue light can reduce bacteria that are involved in periodontitis, but other studies have reported that blue light alone can also reduce bacteria significantly. Therefore, more in-vitro and clinical trial studies are needed to give a more conclusive opinion on the effectiveness of riboflavin as a photosensitizer in the treatment of periodontitis.

Exposure to Blue Wavelength Light Is Associated With Increases in Bidirectional Amygdala-DLPFC Connectivity at Rest

Blue wavelength light has been used successfully as a treatment method for certain mood disorders, but, the underlying mechanisms behind the mood enhancing effects of light remain poorly understood. We investigated the effects of a single dose of 30 min of blue wavelength light (n = 17) vs. amber wavelength light (n = 12) exposure in a sample of healthy adults on subsequent resting-state functional and directed connectivity, and associations with changes in state affect. Individuals who received blue vs. amber wavelength light showed greater positive connectivity between the right amygdala and a region within the left dorsolateral prefrontal cortex (DLPFC). In addition, using granger causality, the findings showed that individuals who received blue wavelength light displayed greater bidirectional information flow between these two regions relative to amber light. Furthermore, the strength of amygdala-DLPFC functional connectivity was associated with greater decreases in negative mood for the blue, but not the amber light condition. Blue light exposure may positively influence mood by modulating greater information flow between the amygdala and the DLPFC, which may result in greater engagement of cognitive control strategies that are needed to perceive and regulate arousal and mood.

First validation results of the new TROPOMI/S5P Total Column Water Vapor product using AERONET ground-based measurements

&lt;p&gt;The very important role of water vapor on the greenhouse effect makes it a species that needs to be continuously and globally monitored, as well as thoroughly studied. The TROPOMI/S5P Total Column Water Vapor (TCWV) is a new product retrieved from the blue wavelength band (435 &amp;#8211;455nm), using an algorithm that was originally developed for GOME-2. The algorithm is based on the DOAS technic and is separately presented in this session*.&lt;/p&gt;&lt;p&gt;The TROPOMI/S5P TCWV product is available for the time period May 2018 to August 2020, almost 2.5 years. For the validation purposes of this work, the co-located precipitable water Level 2.0 (quality-assured) measurements from the NASA AERONET (AErosol RObotic NETwork) were used. The network uses CIMEL sunphotometers located at about 1300 stations globally to monitor precipitable water, among other products. The two datasets, satellite and ground-based, were co-located and the percentage differences of the comparisons were calculated and statistically analyzed. The correlation coefficient of the two products is found to be 0.9 and the mean bias of the relative percentage differences is of the order of 2% for the mid-latitudes and the tropics but increases close to the poles. The effect of various influence quantities, such as air mass factor, solar zenith angle, clouds and albedo are also studied.&lt;/p&gt;&lt;p&gt;*see the respective abstract by Ka Lok Chan (EGU21-2673)&lt;/p&gt;